CSS help with menu/ style.css

I'd like to make the nav-menu a fixed item in the style sheet so that when I want to edit/change it, I only have to do it once. I've done this before, but I can't remember how. I'm using a free template made by freewebsitetemplates.com (specifically, the one called counterstrike). It can be found here: Free Website Templates I would like to add the menu on the left to the style sheet.

Any advice? Thank you!!!

 

The style sheet is seperate from the the template so you should just be able to style your menu from that and it will effect all of your pages.

Just place the new styles in the style sheet not in your html files.

 

and me, I'm using a free template made by freewebsitetemplates.com